Python functools total_ordering() Function

The Python total_ordering() function decorator from the functools module simplifies the implementation of all comparison methods. The functools module is designed to specify the higher-order functions, and the total ordering decorator is a prime example. It enhances the class capabilities without requiring explicit definitions for each comparison method, making the code more maintainable and efficient.

Syntax

Following is the syntax for the total_ordering() function.

@total_ordering()

Parameters

This function doesn't accept any parameters.

Return Value

The decorator returns the class with the additional comparison methods like (__le__, __gt__, __ge__).Below example demosntr

Example 1

The example below, demonstrates a class with methods like __le__, __gt__ and __ge__, which are automatically provided by the total_ordering decorator.

from functools import total_ordering
@total_ordering
class Num:
    def __init__(self, val):
        self.val = val

    def __eq__(self, other):
        return self.val == other.val

    def __lt__(self, other):
        return self.val < other.val
print(Num(31) < Num(12)) 
print(Num(200) > Num(101)) 
print(Num(56) == Num(18))
print(Num(2) != Num(2)) 

Output

The result is generated as follows −

False
True
False
False

Example 2

In this example, the total_ordering() decorator compares word object on the length of their text. By defining the __eq__ and __it__ methods, it automatically provides other comparison methods,simplifying the comparison logic.

from functools import total_ordering
@total_ordering
class Word:
    def __init__(self, txt):
        self.txt = txt

    def __eq__(self, other):
        return len(self.txt) == len(other.txt)

    def __lt__(self, other):
        return len(self.txt) < len(other.txt)
print(Word("grapes") < Word("watermelon"))  
print(Word("banana") < Word("kiwi"))     
print(Word("pineapple") == Word("grape")) 

Output

The code is generated as follows −

True
False
False

Example 3

We are now creating a code that defines a point class with n and p coordinates. Using the total_ordering() decorator, function simplifies the code by defining the __eq__ and __lt__ methods. The decorator allows easy comparison of point objects based on their coordinates.

from functools import total_ordering
@total_ordering
class Point:
    def __init__(self, n, p):
        self.n = n
        self.p = p

    def __eq__(self, other):
        return (self.n, self.p) == (other.n, other.p)

    def __lt__(self, other):
        return (self.n, self.p) < (other.n, other.p)
print(Point(31, 4) < Point(21, 11)) 
print(Point(10, 12) > Point(0, 13)) 
print(Point(2, 2) == Point(1, 1))

Output

The output is obtained as follows −

False
True
False